In fact, I found out the filename of every single file loaded.. and they aren't too hard to change. With this knowledge another possible city loader from LC-Myriad-VC is possible. Simply change the filenames and paths it loads, then force the game to reload.
Here I have written my custom scm's filename - GTAS.SCM - in a code cave located in the memory. And as you can see, each address holds the numeric ascii value of one letter.
Then add 1 to the address and there is the location of the next letter.. you get it.
0x4506E1 - SCM file that GTAVC will load..
|004506E1: PUSH gta-vc.xxxxxx // analysis = ASCII "main.scm",0|
Scroll to 004506E1 in your debugger and you'll see something similiar to this. Change xxxxx to the address containing the binary ascii of your new file, in my case, 0x67dd50. Reload the game and it loads gtas.scm. This information may have been known for a while now, but if so, why hasn't this method been attempted in the making of a city loader? I don't see where it could fail.
So couldn't all GTA:LC files be installed as, say "mainLC.scm" and "gta3LC.img", etc, and then just reload these files to change cities?